1. Field of the Invention
The present invention relates to an electrically driven artificial hand which has a plurality of fingers capable of being opened and closed.
2. Prior Art
The artificial hand means an artificially formed hand which a person having a congenital defect in his upper limb or a postnatal defect in his upper limb due to an accident uses instead of the defected hand.
In Japanese Patent Application Laid-Open No.55-99248, there is disclosed an artificial hand which comprises a plurality of fingers opposite to one another; a grasp part having support members for rotatably supporting a base end part of each of the fingers; an electric artificial hand frame for holding the supporting member; a small-sized motor attached to the artificial hand frame; a reduction mechanism linked to the small-sized motor; a changing mechanism for changing rotating motion of the output part of the reduction mechanism to linear reciprocal motion; and a link mechanism for opening and closing the finger by the linear reciprocal motion of the output part of the changing mechanism.
Further, in Japanese Patent Application Laid-Open No.11-56885, there is disclosed an electric artificial hand which comprises a plurality of fingers opposite to one another; a grasp part having support members for rotatably supporting a base end part of each of the fingers; a solenoid actuator for reciprocally moving its output part; and a link mechanism for opening and closing each of the fingers of the holding part by linking the reciprocal motion of the output part.
A thumb form variable type artificial hand is disclosed in Japanese Patent Application laid-Open No.2201-104349, and a control unit for a electric artificial hand is disclosed in Japanese Patent Application Laid-Open No.10-201782.
As described above, it has been known that the fingers are opened and closed using the link mechanism by changing the rotating motion of the small-sized motor to the linear motion. The finger is supported by the supporting member, and the supporting member is held by the grasp part or a terminal device linked to the hand part, and the terminal device has a rotation hub for changing the direction of the terminal device, that is, the fingertips is arranged at a position corresponding to the human wrist, that is, at a position of a linking part between the wrist part and the terminal device. Accordingly, all of the terminal device and the fingers arranged in front of the wrist must be rotated at the position corresponding to the wrist described above, which requires a little larger motor though it is a small-sized motor.
An object of the present invention is to provide an artificial hand which can sufficiently rotate the whole fingers using a smaller small-sized motor by decreasing the magnitude of the radius of rotation of its rotating motion.
In the present invention, the above-mentioned problem is solved by rotating the terminal device at a position corresponding to the root portion of the fingers.
In the concrete, the present invention provides an artificial hand comprising a plurality of fingers opposite to one another; a support part for rotatably supporting the fingers; a driving device mounted on a grasp part integrated with the support part; and a finger opening-and-closing operation part for converting a rotation output of the driving device to an opening-and-closing operation of the fingers (which may be replaced by a conversion device for converting a rotating output of the driving device to a linear motion, and the linear motion of the conversion device is converted to an opening-and-closing operation), which further comprises a hold part for rotatably holding the support part arranged above or at an upper part of the driving device; a terminal device held by a wrist part; another driving device arranged in the terminal device, a rotating output of the another driving device being converted to a rotational motion of the support part; and a rotating mechanism for rotating the fingers and the driving device around the hold part.
Further, the present invention provides an artificial hand in which the rotating mechanism is constructed of a worm gear rotated by the another driving device; and a rotation gear for rotating the terminal device, the rotation gear being driven by engaging with the worm gear.
Further, the present invention provides an artificial hand in which the rotation gear has a stopper for limiting a rotation angle.